Energy transport from mitochondria to myofibril by a creatine phosphate shuttle in cardiac cells

1983 ◽  
Vol 245 (5) ◽  
pp. C423-C427 ◽  
Author(s):  
G. McClellan ◽  
A. Weisberg ◽  
S. Winegrad
Keyword(s):  
Small Molecules ◽  
Inorganic Phosphate ◽  
Energy Transport ◽  
Adenine Nucleotide ◽  
Surface Membrane ◽  
Creatine Phosphate ◽  
Cardiac Cells ◽  
Bathing Solution ◽  
Resting Tension ◽  
Creatine Phosphate Shuttle

In hyperpermeable cardiac cells, in which the surface membrane has been made highly permeable to small molecules and ions, resting tension increases when the concentration of ATP falls below 200 microM. Peak resting tension occurs in 10 microM ATP and equals 60% of maximum Ca-activated force in 5 mM ATP. The mitochondria in hyperpermeable cells can maintain an ATP concentration above 200 microM if supplied with O2, substrate, ADP, and inorganic phosphate (Pi). Removal of ATP from the bathing solution does not increase resting tension as long as creatine phosphate is present. However O2, substrate, and Pi cannot lower resting tension in the absence of ATP and creatine phosphate. These results are interpreted as evidence for adenine nucleotide tightly bound to the myofibrils and a creatine phosphate shunt of energy from the mitochondria to the myofibrils.

Role of creatine phosphokinase in cellular function and metabolism

1978 ◽  
Vol 56 (5) ◽  
pp. 691-706 ◽  
Author(s):  
V. A. Saks ◽  
L. V. Rosenshtraukh ◽  
V. N. Smirnov ◽  
E. I. Chazov
Keyword(s):  
Energy Transport ◽  
Creatine Phosphokinase ◽  
Surface Membrane ◽  
Creatine Phosphate ◽  
Contractile Force ◽  
Energy Utilization ◽  
Regulatory Factor ◽  
Main Attention ◽  
Intracellular Energy

This paper summarizes the data concerning the role of the creatine phosphokinase system in muscle cells with main attention to the cardiac muscle. Creatine phosphokinase isoenzymes play a key role in the intracellular energy transport from mitochondria to myofibrils and other sites of energy utilization. Due to the existence of the creatine phosphate pathway for energy transport, intracellular creatine phosphate concentration is apparently an important regulatory factor for muscle contraction which influences the contractile force by determining the rate of regeneration of ATP directly available for myosin ATPase, and at the same time controls the activator calcium entry into the myoplasm across the surface membrane of the cells.

Hyperthyroid adult rat cardiomyocytes. I. Nucleotide content, beta- and alpha-adrenoreceptors, and cAMP production

1989 ◽  
Vol 257 (5) ◽  
pp. C948-C956 ◽  
Author(s):  
C. M. Hohl ◽  
S. Wetzel ◽  
R. H. Fertel ◽  
D. K. Wimsatt ◽  
G. P. Brierley ◽  
...  
Keyword(s):  
Ventricular Myocytes ◽  
Adenine Nucleotide ◽  
Phosphodiesterase Inhibitor ◽  
Cardiac Cells ◽  
Beta Agonist ◽  
Camp Production ◽  
Adult Rats ◽  
Rat Cardiomyocytes ◽  
Adult Rat ◽  
Half Maximal Effective Concentration

Ventricular myocytes isolated from the hypertrophied hearts of thyrotoxic adult rats have an increase in mean protein content per myocyte (6.3 +/- 0.2 vs. 4.4 +/- 0.2 ng) compared with euthyroid cells. Viability and adenine nucleotide profiles are similar in both populations, but NAD content of the hyperthyroid myocytes is depressed (4.9 +/- 0.2 vs. 5.5 +/- 0.2 nmol/mg for controls) and UTP is higher (1.2 +/- 0.09 vs. 0.9 +/- 0.04 nmol/mg). Binding of (-)-[125I]iodocyanopindolol to intact hyperthyroid myocytes is increased by 42% compared with controls, with no change in the dissociation constant (Kd). This elevation in beta-receptor number is correlated to enhanced beta-agonist-induced adenosine 3',5'-cyclic monophosphate (cAMP) production. The half-maximal effective concentration (EC50) for the euthyroid isoproterenol dose-response curve is 2.14 x 10(-7) M but is decreased to 2.51 x 10(-8) M in hyperthyroid cardiac cells. Basal adenylate cyclase activity is apparently not affected by thyroid hormones, since basal cAMP levels for both groups are identical (5 pmol/mg) and both rise roughly twofold in the presence of a phosphodiesterase inhibitor. Forskolin-induced cAMP production and cAMP-specific phosphodiesterase activity are similar as well. In contrast to beta-adrenergic response, there are no significant differences in alpha 1-antagonist [3H]prazosin binding parameters between hyperthyroid and euthyroid cardiomyocytes.

Dissociation of hypoxia-induced calcium gain and rise in resting tension in isolated rat hearts

1988 ◽  
Vol 254 (4) ◽  
pp. H678-H685
Author(s):  
W. G. Nayler ◽  
J. S. Elz ◽  
D. J. Buckley
Keyword(s):  
Perfusion Defect ◽  
Creatine Phosphate ◽  
Ventricular Muscle ◽  
Isolated Hearts ◽  
Resting Tension ◽  
Rat Hearts ◽  
Early Increase ◽  
Butanedione Monoxime ◽  
Tension Generation ◽  
Isolated Rat

When isolated hearts are perfused with substrate-free hypoxic buffer for prolonged periods of time, resting tension and tissue Ca increase. These two events may be interrelated. Isolated rat hearts were used to establish whether the hypoxia-induced increase in tissue Ca can be dissociated from the rise in resting tension. Tension generation was inhibited at the start of hypoxic perfusion by adding 2,3-butanedione monoxime (BDM, 30 mM). In other experiments the Ca2+ in the hypoxic buffer was reduced from 1.3 to 0.1 mM. After 30-120 min of hypoxia, ventricular muscle was assayed for ATP, creatine phosphate, Ca, and Na, and the perfusion defect was established. Resting tension was recorded before and throughout the hypoxic perfusion. Sixty minutes of perfusion with 1.3 mM Ca2+ glucose-free hypoxic buffer caused the tissue Ca to increase (P less than 0.01). Resting tension increased by 7.9 +/- 0.6 g (P less than 0.01). Sixty minutes of perfusion with 0.1 mM Ca2+ glucose-free hypoxic buffer failed to cause an increase in tissue Ca, but resting tension increased (P less than 0.01). During perfusion with glucose-free hypoxic buffer containing 2.6 mM Ca2+ and 30 mM BDM, resting tension remained low for up to 120 min, but after 60 min Ca accumulation occurred. After 120 min of BDM-hypoxic perfusion, tissue Ca reached 11.8 +/- 0.9 mumol/g dry wt. With or without BDM, hypoxia caused an early increase in tissue Na ahead of any increase in tissue Ca.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals The Effect of Bathing Solution Tonicity on Resting Tension in Frog Muscle Fibers

1973 ◽  
Vol 62 (6) ◽  
pp. 737-755 ◽  
Author(s):  
J. Lännergren ◽  
J. Noth
Keyword(s):  
Cross Section ◽  
Short Range ◽  
Muscle Fibers ◽  
Bathing Solution ◽  
Direct Function ◽  
Fiber Cross Section ◽  
Resting Tension ◽  
Hypertonic Solutions ◽  
Cross Section Area ◽  
Section Area

Resting tension and short-range elastic properties of isolated twitch muscle fibers of the frog have been studied while bathed by solutions of different tonicities. Resting tension in isotonic solution at 2.3-µm sarcomere spacing averaged 0.46 mN·mm-2 and was proportional to the fiber cross-section area. Hypertonic solutions, containing 0.1–0.5 mM tetracaine to block contracture tension, caused a small sustained tension increase, which was proportional to the fiber cross-section area and which reached 0.9 mN·mm-2 at two times normal tonicity (2T). Further increases in tonicity caused little increase in tension. Hypotonic solutions decreased tension. Thus, tension at 2.3 µm is a continuous, direct function of tonicity. The dependence of tension on tonicity lessened at greater sarcomere lengths. At 3.2 µm either a very small rise or, in some fibers, a fall in tension resulted from an increase in tonicity. Hypertonic solutions also decreased the tension of extended sarcolemma preparations. In constant-speed stretch experiments the elastic modulus, calculated from the initial part of the stretch response, rose steeply with tonicity over the whole range investigated (1–2.5T). The results show that tension and stiffness of the short-range elastic component do not increase in parallel in hypertonic solutions.

scholarly journals The Capacitance of Skeletal Muscle Fibers in Solutions of Low Ionic Strength

1972 ◽  
Vol 59 (3) ◽  
pp. 347-359 ◽  
Author(s):  
P. C. Vaughan ◽  
J. N. Howell ◽  
R. S. Eisenberg
Keyword(s):  
Skeletal Muscle ◽  
Ionic Strength ◽  
Surface Membrane ◽  
Muscle Fibers ◽  
External Solution ◽  
Rectangular Pulse ◽  
Bathing Solution ◽  
Skeletal Muscle Fibers ◽  
Tubular System ◽  
Low Ionic Strength

The capacitance of skeletal muscle fibers was measured by recording with one microelectrode the voltage produced by a rectangular pulse of current applied with another microelectrode. The ionic strength of the bathing solution was varied by isosmotic replacement of NaCl with sucrose, the [K] [Cl] product being held constant. The capacitance decreased with decreasing ionic strength, reaching a value of some 2 µF/cm2 in solutions of 30 mM ionic strength, and not decreasing further in solutions of 15 mM ionic strength. The capacitance of glycerol-treated fibers did not change with ionic strength and was also some 2 µF/cm2. It seems likely that lowering the ionic strength reduces the capacitance of the tubular system (defined as the charge stored in the tubular system), and that the 2 µF/cm2 which is insensitive to ionic strength is associated with the surface membrane. The tubular system is open to the external solution in low ionic strength solutions since peroxidase is able to diffuse into the lumen of the tubules. Twitches and action potentials were also recorded from fibers in low ionic strength solutions, even though the capacitance of the tubular system was very small in these solutions. This finding can be explained if there is an action potential—like mechanism in the tubular membrane.

Comparison in control and severely diabetic, alloxanized rats of phosphate fractions, glycogen and fat

1959 ◽  
Vol 196 (6) ◽  
pp. 1246-1249 ◽  
Author(s):  
Clarissa H. Beatty ◽  
Ruth D. Peterson ◽  
Rose Mary Bocek ◽  
Edward S. West
Keyword(s):  
Body Weight ◽  
Inorganic Phosphate ◽  
Trichloroacetic Acid ◽  
Adenosine Diphosphate ◽  
Creatine Phosphate ◽  
Soluble Phosphate ◽  
Total Acid ◽  
Control Series ◽  
Noncollagenous Protein ◽  
Total Muscle

Homogeneous aliquots of powdered muscle were analyzed and levels of constituents calculated on a fat-free basis. When compared to muscle from control rats, muscle from severely diabetic, alloxanized rats showed a decrease in creatine phosphate, total acid soluble phosphate and total phosphate, with no change in inorganic phosphate, adenosine diphosphate plus adenosine triphosphate, or total acid soluble phosphate minus 7-minute hydrolyzable phosphate, creatine, noncollagenous protein or total nitrogen. There was an increase in the trichloroacetic acid extractable glycogen value in the muscle of the alloxan diabetic as compared to the control series. The concentration of fat in the muscle itself was higher in the diabetic than in the control series, although the total muscle fat had decreased in the diabetic series due to the decrease in percentage of body weight represented by muscle.

Myocardial adenine pool depletion and recovery of mechanical function following ischemia

1985 ◽  
Vol 248 (5) ◽  
pp. H644-H651
Author(s):  
S. M. Humphrey ◽  
D. G. Holliss ◽  
R. N. Seelye
Keyword(s):  
Inorganic Phosphate ◽  
Time Course ◽  
Creatine Phosphate ◽  
Limiting Factor ◽  
Ischemia And Reperfusion ◽  
Mechanical Function ◽  
Rat Hearts ◽  
Complete Failure ◽  
Hemodynamic Function ◽  
Mechanical Recovery

The loss of nucleotide pool precursors from the heart during ischemia and reperfusion may affect resynthesis of ATP and consequently mechanical recovery. Isolated working rat hearts were made globally ischemic for from 15 to 25 min, and the tissue content of adenine pool metabolites, creatine, creatine phosphate (CP), and inorganic phosphate (Pi), were measured after 20 min of reperfusion. In addition, the coronary effluent was assayed for nucleotides, nucleosides, and oxypurines. Hearts that recovered 75% or more of their preischemic hemodynamic function had significantly lower ATP and NAD but greater CP and Pi than controls. Complete failure of hearts was associated with severely depleted ATP but not CP. All hearts released 25% or more of their preischemic adenine pool during the 20-min reperfusion. This loss correlated more closely with a reduction in recovery from 100 to 75% than with complete failure. Thus extensive loss of adenine pool precursors is not critically related to the failure of heart muscle to recover function but may be an important limiting factor in determining the extent and time course of mechanical recovery.

scholarly journals Investigation of the Accompaniment of Calcium During Active Calcium Transport from Human Erythrocyte Ghosts

1974 ◽  
Vol 63 (5) ◽  
pp. 590-600 ◽  
Author(s):  
Erik J. Olson ◽  
Ralph J. Cazort
Keyword(s):  
Cell Membrane ◽  
Calcium Transport ◽  
Inorganic Phosphate ◽  
Adenine Nucleotide ◽  
Erythrocyte Ghosts ◽  
High Dilutions ◽  
A Cell ◽  
Active Calcium ◽  
Phosphate Analysis ◽  
Almost All

To determine whether a cell metabolite was involved in active calcium transport, the cell contents of human erythrocytes were subjected to high dilutions and the resultant ghosts were checked for their ability to actively transport calcium. It was found that the diluted erythrocyte ghosts did retain their capacity to actively transport calcium and that the characteristics of this transport process appeared to be unaltered by the high dilutions. Calcium analysis of the cell membrane and cell supernatant indicated that almost all of the calcium was lost from the cell solution rather than the cell membrane as active calcium transport proceeded. Therefore it appeared that calcium was able to cross the cell membrane without the aid of a cell metabolite. Investigations with layered erythrocytes indicated that the active transport of calcium was not assisted by centrifugation. Neither inorganic phosphate, pyrophosphate, nor an adenine nucleotide appeared to accompany calcium across the membrane as indicated by total phosphate and inorganic phosphate analysis and 260-nm readings of the deproteinized supernatant.

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